Figure 1.
NS Mutants Delete Lateral Leaf Domains Due to Loss of NS Function in Lateral Foci of the SAM
(A and B) The ns mutant leaf (B) contains a developmental deletion of a large lateral domain present in nonmutant leaves (A). In situ hybridization reveals NS1 transcript accumulation (C) and modeled in (D) in two lateral foci during initiation of a new leaf primordium (1) from the SAM.
(E) Drawings of leaf initiation from the SAM are depicted in longitudinal (top) and transverse (bottom) sections. Leaf founder-cell initiation begins on one SAM flank that gives rise to the midrib and central domain of the leaf primordium (faint pink in [E–G]). NS1 function (red arrows in [E]) is required to complete founder cell recruitment of lateral domains of the leaf that includes the margin (dark pink in [E and F]). Loss of the NS1 recruitment function results in failure to recruit this lateral leaf domain (B) and (G). Images in (A, B, and C) are reproduced with permission from Nardmann et al. [2].
Figure 2.
LM of the SAM from Paraffin Sections of Maize Seedlings
(A) The apex before LM is shown.
(B) Laser ablation is used to isolate the SAM from surrounding leaf primordia and stem tissue, without heating or damaging adjacent SAM tissues.
(C) SAM tissue is microdissected via laser pressure catapulting, in which the laser is focused beneath the targeted SAM tissue and a high photonic force catapults the tissue into a collection tube suspended above the sample.
Table 1.
Genes Differentially Expressed in the ns1 SAM
Figure 3.
Predicted Functions of 66 Genes Differentially Expressed in the ns1-R Mutant SAM
Excluding unknowns and housekeeping genes, 28/40 genes are predicted to function during hormonal-cellular signaling or growth and cell division.
Figure 4.
Identification of Shoot Meristem-Enriched Maize Transcripts by qRT-PCR Analyses of Multiple Maize Tissues
(A) Transcripts of the DEAD box helicase-like gene DV621960 and the (B) response regulator-like gene BG840771 are enriched in the SAM, whereas (C) the yabby-like gene CD650947 is up-regulated in inflorescence tissues bearing floral meristems as well as in the SAM.
(D) Control expression pattern of knotted1 is shown, which is enriched in shoot meristems.
Figure 5.
In Situ Hybridization Reveals Domain-Specific Expression of Differentially Expressed Maize Genes in Nonmutant and ns1-R Mutant Shoot Apices, Part I.
Drawings of SAM expression patterns are modeled in (C and D), (G and H), (K and L), (O and P), and (S and T). Differentially expressed maize genes shown in nonmutant (wild type: [A], [E], [I], [M], and [Q]) and ns1-R mutant (ns: [B], [F], [J], [N], and [R]) shoot apices. No expression in leaf primordia is portrayed in cartoons, since transcripts accumulating in leaves were not LM sampled or reflected in microarray data. Probes were made from maize ESTs: DV621960 (A and B), CD001847 (E and F), DN210415 (I and J), Zmhp1 (M and N), and DN221438 (Q and R).
Predicted functions are abbreviated as: helicase, DEAD BOX HELICASE; hp1, HISTIDINE PHOSPHOTRANSFER PROTEIN1; tir1, TRANSPORT INHIBITOR RESPONSE F-BOX protein; jac1, JACALIN-related LECTIN; and GTPase, Rab class GTP-BINDING SIGNAL TRANSDUCER. Numbers denote leaf primordia. Analyses of expression patterns are provided in the text.
Table 2.
qRT-PCR Corroboration of ns1-R Differentially Expressed Genes
Figure 6.
In Situ Hybridization Reveals Domain-Specific Expression of Differentially Expressed Maize Genes in Nonmutant and ns1-R Mutant Shoot Apices, Part II
Drawings of SAM expression patterns are modeled in (C and D), (G and H), (K and L), and (N and P). Differentially expressed maize genes are shown in nonmutant (wild type: [A], [E], [I], [M], and [O]) and ns1-R mutant (ns: [B], [F], and [J]) shoot apices. No expression in leaf primordia is portrayed in drawings, since transcripts accumulating in leaves were not LM sampled or reflected in microarray data. Probes were made from maize ESTs: DN232668 (A and B), DY400928 (E and F), AI820200 (I and J), CB381550 (M), and CD650947 (O). Predicted functions are abbreviated as: ara GTPase, GTP-BINDING PROTEIN ARA-3; sugar trans, SUGAR TRANSPORTER PROTEIN; amine oxidase, AMINE OXIDASE1; FtsZ, CELL DIVISION FTSZ PROTEIN; and Yabby, YABBY-RELATED PROTEIN. Numbers denote leaf primordia. Analyses of expression patterns are provided in the text.